SORDELLI Daniel Oscar
congresos y reuniones científicas
Molecular characterization of quinolone and antiseptic resistance in coagulase-negative staphylococci. Abstract P-124
JERIC, PAOLA E.; AZPIROZ, MARIA A.; DE PAULIS, ADRIANA N.; PREDARI, SILVIA C.; SORDELLI, DANIEL O.
Simposio; 12th International Symposium on Staphylococci and Staphylococcal Infections (ISSSI); 2006
The presence of efflux mechanisms of resistance was investigated in Staphylococcus epidermidis clinical isolates from patients with infections associated to endovascular catheters, vesical catheters and ambulatory continuous peritoneal dialysis (dialysis fluid samples). Association of efflux mechanisms with biofilm formation was assessed. Sixty-two clinical isolates resistant to ciprofloxacin were collected and the MIC to nalidixic acid, norfloxacin, ciprofloxacin, levofloxacin and moxifloxacin was determined using the dilution method. To detect efflux mechanisms of resistance the MIC to ciprofloxacin and ethidium bromide was determined in the presence/absence of efflux inhibitor carbonyl-cyanide-m-chlorophenylhydrazone (CCCP). We searched by PCR the genes qacA, qacB, smr, mecA and the operon icaADBC. Biofilm formation was tested by the crystal violet assay. All 62 isolates were resistant to norfloxacin (16-128 ìg/ml), ciprofloxacin (4-256 ìg/ml), levofloxacin (1-8 ìg/ml), but susceptible to moxifloxacin (0,5-2 ìg/ml). Sixty-one (98.4%) isolates harboured the mecA gene and 60 (96.8%) the icaADBC operon (biofilm formation). From these 62 isolates, 17 (27.4%) showed a significant decrease in the MIC to ciprofloxacin in the presence of CCCP. Forty-two isolates (67.7%) showed a decrease in MIC values to ethidium bromide in the presence of CCCP, but only 12 (19.4%) showed also efflux to quinolones. The smr gene was detected in all 62 isolates (100%) whereas qacA/B gene was detected in 13 (21%) of them. In spite of harbouring qacA/B and smr, 4 isolates (6.4 %) did not express efflux to ethidium bromide and 15 (24.2 %) that harboured only smr did not express it either. Most of the isolates that did not express efflux were weak biofilm producers. In conclusion, there seems to be no common pump for different compounds. Furthermore, efflux to quinolones does not appear to be the only mechanism present in these isolates, and those isolates that expressed efflux were also biofilm producers, suggesting that they could have an advantage for adherence thus making them more virulent.